[libc++] Replace __sync_* functions with __libcpp_atomic_* functions

Summary:
This patch replaces __sync_* with __libcpp_atomic_* and adds a wrapper
function for __atomic_exchange to support _LIBCPP_HAS_NO_THREADS.

Reviewers: EricWF, jroelofs, mclow.lists, compnerd

Reviewed By: EricWF, compnerd

Subscribers: compnerd, efriedma, cfe-commits, joerg, llvm-commits

Differential Revision: https://reviews.llvm.org/D35235

llvm-svn: 313694

2 files changed, 6 insertions, 7 deletions

diff --git a/libcxx/src/support/runtime/exception_fallback.ipp b/libcxx/src/support/runtime/exception_fallback.ipp
index 69c06a9ce3a..664e7f48c09 100644
--- a/libcxx/src/support/runtime/exception_fallback.ipp
+++ b/libcxx/src/support/runtime/exception_fallback.ipp
@@ -20,13 +20,13 @@ _LIBCPP_SAFE_STATIC static std::unexpected_handler __unexpected_handler;
 unexpected_handler
 set_unexpected(unexpected_handler func) _NOEXCEPT
 {
-  return __sync_lock_test_and_set(&__unexpected_handler, func);
+  return __libcpp_atomic_exchange(&__unexpected_handler, func);
 }
 
 unexpected_handler
 get_unexpected() _NOEXCEPT
 {
-  return __sync_fetch_and_add(&__unexpected_handler, (unexpected_handler)0);
+  return __libcpp_atomic_load(&__unexpected_handler);
 
 }
 
@@ -41,14 +41,13 @@ void unexpected()
 terminate_handler
 set_terminate(terminate_handler func) _NOEXCEPT
 {
-  return __sync_lock_test_and_set(&__terminate_handler, func);
+  return __libcpp_atomic_exchange(&__terminate_handler, func);
 }
 
 terminate_handler
 get_terminate() _NOEXCEPT
 {
-  return __sync_fetch_and_add(&__terminate_handler, (terminate_handler)0);
-
+  return __libcpp_atomic_load(&__terminate_handler);
 }
 
 #ifndef __EMSCRIPTEN__ // We provide this in JS
diff --git a/libcxx/src/support/runtime/new_handler_fallback.ipp b/libcxx/src/support/runtime/new_handler_fallback.ipp
index b7092d542d9..ec3f52354ca 100644
--- a/libcxx/src/support/runtime/new_handler_fallback.ipp
+++ b/libcxx/src/support/runtime/new_handler_fallback.ipp
@@ -15,13 +15,13 @@ _LIBCPP_SAFE_STATIC static std::new_handler __new_handler;
 new_handler
 set_new_handler(new_handler handler) _NOEXCEPT
 {
-    return __sync_lock_test_and_set(&__new_handler, handler);
+    return __libcpp_atomic_exchange(&__new_handler, handler);
 }
 
 new_handler
 get_new_handler() _NOEXCEPT
 {
-    return __sync_fetch_and_add(&__new_handler, nullptr);
+    return __libcpp_atomic_load(&__new_handler);
 }
 
 } // namespace std